<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
/*
常见的高阶函数:  setTimeout, setInterval

map:

reduce:

filter:
    
    这三个都不会对原数组产生影响
 */
var arr = [1, 2, 3, 4, 50];   // [1, 2, 9, 16, 25]
var a1 = arr.filter(function (ele, index, array){
    return ele % 2 == 1
})
console.log(a1);
</script>
</body>
</html>